JP2006278947A - Board, camera module equipped therewith and method of mounting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further improve the reliability of soldering with respect to a board, a camera module equipped with this board, and a method of mounting the board. <P>SOLUTION: Junction top surfaces 102A of top flat portions 102 of a plate spring 100 are soldered on bump lands 54 formed on a board 53 of a BGA package 51, and the junction bottom surface 104A of the bottom flat portion 104 of the plate spring 100 is soldered on a land 61 formed on the top surface of a printed board 52, thereby mounting the BGA package 51 of the printed board 52. In this way, since the plate spring 100 elastically deforms to absorb a variation in height, the reliability of soldering is excellent. Moreover, stress applied due to a difference in thermal expansion between the BGA package 51 and the printed board 52 after mounting can be absorbed by the elastic deformation of the plate spring 100. As a result, for example, a crack or breakage is not generated in the solder. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a board, a camera module including the board, and a board mounting method.

  In recent years, a BGA (Ball Grid Array) package has been introduced as a package corresponding to circuit digitization and high speed as a trend of substrates.

  In the BGA package, a plurality of bump lands are formed on the lower surface, and solder balls are formed on the bump lands. On the other hand, the motherboard has a plurality of motherboard lands formed thereon by printing. Then, the BGA package is placed on the motherboard, heated in a nitrogen gas atmosphere, solder balls are melted (reflowed), and the bump land of the BGA package and the motherboard land of the motherboard are soldered.

  However, in the conventional configuration described above, when the solder balls are formed, the height often varies. For this reason, it is inevitable that a soldering failure occurs at a certain rate. Further, even after mounting, mechanical stress is applied to the soldered portion due to the difference in thermal expansion coefficient between the BGA package and the mother board, which may cause cracks or breakage.

For this reason, a conductive column processed into a helical spring is interposed between the bump land of the BGA package and the motherboard land of the motherboard, and the bump land and the motherboard land are soldered by the column. Thus, a configuration has been proposed that relieves the mechanical stress applied to the height variation and the soldered portion. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 08-139226

  However, even in the method described in Japanese Patent Application Laid-Open No. 08-139226, the helical spring column itself varies. Also, the helical spring-like column has a configuration in which a metal wire or the like is spirally wound, so that the soldering solder is transmitted to the middle portion of the column and is covered with the solder. For this reason, the spring property of the column is impaired, and the mechanical stress applied to the solder due to the difference in thermal expansion coefficient between the BGA package and the mother board cannot be sufficiently buffered. Therefore, further improvement in the reliability of soldering is required.

  The present invention has been made to solve the above problems, and an object thereof is to further improve the reliability of soldering.

  To achieve the above object, the substrate according to claim 1 is a substrate in which a package substrate on which a semiconductor chip is mounted is mounted on a printed circuit board, and the electrode of the package substrate and the electrode of the printed circuit board are: Either one of the one end and the other end, or both ends are joined via a conductive elastic member having a substantially horizontal plane, and one end of the elastic member is soldered to the electrode of the package substrate, and the electrode of the printed circuit board is the electrode The other end of the elastic member is soldered.

  In the substrate according to claim 1, one end of a conductive elastic member is soldered to the electrode of the package substrate, and the other end of the elastic member is soldered to the electrode of the printed circuit board. The electrode is joined.

  Therefore, since the elastic member is elastically deformed and absorbs the variation in height, the reliability of soldering is high. Further, the stress due to the difference in thermal expansion between the package substrate and the printed circuit board after mounting is also absorbed by the elastic deformation of the elastic member. Therefore, for example, since solder does not crack or break, good bonding is maintained over a long period of time.

  Furthermore, the conductive elastic member has a substantially horizontal surface at one or both ends of the one end and the other end. Therefore, since it solders on a surface (substantially horizontal surface), it is easy to perform soldering. Also, the soldering strength is high. Further, since the solder on the surface (substantially horizontal plane) is difficult to move to other portions of the elastic member, it does not hinder the elastic deformation of the elastic member.

  Thus, the reliability of soldering has been remarkably improved over a long period.

  According to a second aspect of the present invention, in the configuration according to the first aspect, at least the electrode of the package substrate and the electrode of the printed circuit board that are most stressed are joined via the elastic member. It is characterized by that.

  In the substrate according to claim 2, since the electrode of the package substrate and the electrode of the printed circuit board, which are most stressed, are joined via an elastic member, the reliability of soldering is long-term. It has improved.

  The substrate according to claim 3 is the configuration according to claim 2, wherein the electrodes of the outermost package substrate and the electrodes of the printed circuit board are arranged in a substantially rectangular shape, and at least the package substrates at the four corners of the outermost periphery. The electrode of the printed circuit board and the electrode of the printed circuit board are joined by the elastic member.

  In the substrate according to claim 3, the electrode of the outermost package substrate and the electrode of the printed circuit board are arranged in a substantially square shape, and at least the electrode of the package substrate and the electrode of the printed circuit board at the four corners of the outermost periphery are conductive. It is joined with the elastic member.

  The stress due to the difference in thermal expansion between the package substrate and the printed circuit board is most applied to the four corners of the outermost periphery arranged in a substantially rectangular shape. Therefore, the reliability of soldering is improved over a long period of time by joining the electrode of the package substrate and the electrode of the printed circuit board at the outermost four corners where stress is most affected by the conductive elastic member.

  According to a fourth aspect of the present invention, in the configuration according to any one of the first to third aspects, the elastic member includes an intermediate portion between the both ends where the solder is less likely to adhere to the both ends. It is characterized by that.

  According to the fourth aspect of the present invention, since the solder hardly adheres to the middle portion of the elastic member, the elastic deformation of the elastic member is not hindered. Therefore, bonding is maintained better over a long period of time.

  According to a fifth aspect of the present invention, in the structure according to any one of the first to fourth aspects, the elastic member is a leaf spring.

  In the substrate according to the fifth aspect, since the electrode of the package substrate and the electrode of the printed circuit board are joined via a leaf spring, the reliability of soldering is remarkably improved over a long period of time.

  A camera module according to a sixth aspect includes the substrate according to any one of the first to fourth aspects.

  The camera module according to claim 6 includes the substrate according to any one of claims 1 to 5 in which the reliability of soldering has been remarkably improved over a long period of time. It is a high camera module.

  The substrate mounting method according to claim 7 is a substrate mounting method for mounting a package substrate on which a semiconductor chip is mounted on a printed circuit board, wherein a predetermined region of a conductive plate is cut out, and the package substrate is cut out. A first step of forming leaf springs in an array corresponding to the electrodes of the first plate, and soldering the other end of the leaf springs formed on the plate with solder balls previously formed on the electrodes of the package substrate. A second step of bonding the plate spring to the electrode of the substrate; a third step of removing the plate spring bonded to the electrode of the package substrate from the plate; and the bonding of the plate spring to the first electrode of the package substrate. One end of the leaf spring is soldered with a solder ball previously formed on the electrode of the printed circuit board, and a fourth screw is joined to the electrode of the printed circuit board. Is characterized in that it has Tsu and up, the.

  In the substrate mounting method according to claim 7, the predetermined region of the conductive plate is cut out, and the plate spring is formed in an arrangement corresponding to the electrode of the package substrate. Easy to solder.

  Further, since the leaf spring is elastically deformed and absorbs variations in height, the reliability of soldering is high. Furthermore, the stress applied due to the difference in thermal expansion between the package substrate and the printed circuit board after mounting is also absorbed by the elastic deformation of the leaf spring. Therefore, for example, since solder does not crack or break, good bonding is maintained over a long period of time.

  The substrate mounting method according to claim 8 is a substrate mounting method for mounting a package substrate on which a semiconductor chip is mounted on a printed circuit board, wherein solder balls are formed on both surfaces of a conductive plate. One step, a second step of cutting out a predetermined region of the plate and forming plate springs having the solder balls on both ends in an arrangement corresponding to the electrodes of the package substrate, and the plate formed on the plate One end of a spring is soldered to the electrode of the package substrate with the solder ball, and the third step of joining the leaf spring to the electrode of the package substrate, and the plate joined to the electrode of the package substrate A fourth step of removing the leaf spring, and the other end of the leaf spring joined to the electrode of the package substrate with the solder ball, Soldered to the poles, it is characterized by having a fifth step of bonding the plate spring to the electrodes of the printed circuit board, the.

  The substrate mounting method according to claim 9 is a substrate mounting method in which a package substrate on which a semiconductor chip is mounted is mounted on a printed circuit board, and solder balls are formed on one surface of a conductive plate. A first step, a second step of cutting out a predetermined region of the plate and forming a plate spring having the solder ball at one end in an arrangement corresponding to the electrode of the package substrate; and the plate formed on the plate A third step of soldering one end of a leaf spring to the electrode of the package substrate with the solder ball, and joining the leaf spring to the electrode of the package substrate, and joining the electrode of the package substrate from the plate The fourth step of removing the leaf spring and the other end of the leaf spring joined to the electrode of the package substrate in advance to the electrode of the printed circuit board. And soldering made solder balls, are characterized by having a fifth step of bonding the plate spring to the electrodes of the printed circuit board, the.

  The substrate mounting method according to claim 10 is a substrate mounting method for mounting a package substrate on which a semiconductor chip is mounted on a printed circuit board, wherein solder balls are formed on the other surface of the conductive plate. A second step of cutting out a predetermined region of the plate and forming a plate spring having the solder ball at the other end in an arrangement corresponding to the electrode of the package substrate; and the step formed on the plate A third step of soldering one end of the leaf spring with a solder ball previously formed on the electrode of the package substrate, and joining the leaf spring to the electrode of the package substrate, and from the plate to the electrode of the package substrate The fourth step of removing the joined leaf spring and the other end of the leaf spring joined to the electrode of the package substrate are connected with the solder ball by the solder ball. Soldered to the electrodes of the cement board it is characterized by having a fifth step of bonding the plate spring to the electrodes of the printed circuit board, the.

  In the substrate mounting method according to any one of claims 8 to 10, solder balls are formed in advance on one or both surfaces of one side and the other side of the plate, and a predetermined region of the plate is cut out. Since the leaf springs having solder balls on one or both of the one end and the other end are formed in the array corresponding to the electrodes of the package substrate, the package substrate can be easily mounted on the printed circuit board.

  As described above, the present invention has improved soldering reliability over a long period of time.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, an external configuration of the digital camera 10 according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, the digital camera 10 shoots a lens 21 for forming a subject image on the front surface of the camera housing 11, a strobe 62 that emits light to irradiate the subject as necessary during photographing, and photographing. A finder 88 used to determine the composition of the subject is provided. In addition, the digital camera 10 includes a release button (so-called shutter) 92 and a power switch 94 that are pressed by the user when shooting is performed on the upper surface of the camera housing 11.

  Note that the release button 92 of the digital camera 10 according to the present embodiment is pressed down to an intermediate position (hereinafter referred to as “half-pressed state S1”), and pressed to a final pressed position that exceeds the intermediate position. 2 states (hereinafter referred to as “fully pressed state S2”) can be detected. In the digital camera 10, when the release button 92 is half-pressed in the state S1, an AE (Automatic Explosure, meaning automatic exposure) function works and the exposure state (shutter speed, aperture state) is changed. After the setting, the AF (abbreviation of Auto Focus, meaning automatic focusing) function is operated and focusing control is performed, and then exposure (photographing) is performed when the shutter button is fully pressed S2. Yes.

  On the other hand, the eyepiece of the finder 88 is provided on the back of the camera housing 11. In the vicinity of the eyepiece portion of the finder 88 (downward in FIG. 1), a liquid crystal display 44 (hereinafter referred to as “hereinafter,“ a subject image, various menu screens, messages, etc.) indicated by digital image data obtained by photographing. LCD 44 "). Further, a mode change switch 96 is provided near the LCD 44 (upward in FIG. 1), and a cross cursor button 98 is provided near the LCD 44 (right side in FIG. 1). The mode switch 96 is either a shooting mode that is a mode for performing shooting by a slide operation by a user or a playback mode that is a mode for displaying (reproducing) a subject image indicated by digital image data obtained by shooting. It is for setting to one of these modes. The cross cursor button 98 is a total of five keys including four arrow keys indicating the upward, downward, left, and right movement directions in the display area of the LCD 44 and a determination key positioned at the center of the four arrow keys. The corresponding command is output when each key is pressed. In addition, in the vicinity of the cross cursor button 98 (upward in FIG. 1), a forced light emission switch 99 for setting a forced light emission mode, which is a mode in which the strobe 62 is forced to emit light at the time of shooting by a user's pressing operation, is provided. It has been.

  Next, the configuration of the electrical system of the digital camera 10 according to the present embodiment will be described with reference to FIG.

  The digital camera 10 includes a camera module 12. The camera module 12 includes an optical unit 22 configured to include a lens 21 (see FIG. 1). A charge-coupled device 24 (hereinafter referred to as “CCD 24”) is provided behind the optical axis of the lens 21 on the exit side of the optical unit 22. ") Is provided. The CCD 24 is connected to the system bus BUS via an analog signal processing unit 26, an analog / digital converter 28 (hereinafter referred to as “ADC 28”), and a digital signal processing unit 30. The analog signal processing unit 26 is configured to include a circuit that obtains accurate pixel data by reducing noise (particularly thermal noise) included in the output signal of the CCD. The ADC 28 is for converting an input analog signal into digital data. The digital signal processing unit 30 has a built-in line buffer having a predetermined capacity, and performs control for directly storing the input digital image data in a predetermined area of the memory 72, and various digital images are applied to the digital image data. The processing is performed.

  Note that the digital signal processing unit 30, the LCD interface 42, the CPU (central processing unit) 50, the memory interface 70, the external memory interface 80, and the compression / decompression processing circuit 86 are mutually connected to the system bus BUS. Is connected to accept and receive. The LCD interface 42 is an interface circuit that generates a signal for causing the LCD 44 to display an image or a menu screen indicated by the digital image data and supplies the signal to the LCD 44. A CPU (Central Processing Unit) 50 is a processing unit that controls the operation of the entire digital camera 10. The memory 72 is a memory composed of a VRAM (Video RAM) that mainly stores digital image data obtained by photographing. The memory interface 70 is a control circuit for accessing the memory 72. The external memory interface 80 is an interface circuit that allows the digital camera 10 to access a memory card 82 formed of a recording medium such as Smart Media (registered trademark). The compression / decompression processing circuit 86 is a processing circuit that performs compression processing on digital image data in a predetermined compression format, and performs decompression processing on the compressed digital image data according to the compression format.

  Therefore, the CPU 50 controls the operation of the digital signal processing unit 30 and the compression / decompression processing circuit 86, displays various information to the LCD 44 via the LCD interface 42, the memory interface 70 to the memory 72 and the memory card 82, and the external memory interface. Access through 80.

  On the other hand, the digital camera 10 includes a timing generator 32 that mainly generates a timing signal for driving the CCD 24 and supplies the timing signal to the CCD 24, and the driving of the CCD 24 is controlled by the CPU 50 via the timing generator 32.

  The digital camera 10 also includes a drive unit 34, and the driving of the focus adjustment mechanism (details will be described later), the zoom mechanism, and the aperture drive mechanism provided in the optical unit 22 is also controlled by the CPU 50 via the drive unit 34. .

  When changing the optical zoom magnification, the CPU 50 drives and controls a zoom mechanism (not shown) to change the focal length of the lens 21 included in the optical unit 22. Further, the CPU 50 performs focus control by driving and controlling the focus adjustment mechanism (described later) so that the contrast value of the image obtained by imaging by the CCD 24 is maximized. The digital camera 10 according to the present embodiment employs a so-called TTL (Through The Lens) method in which the lens position is set so that the contrast of the read image is maximized as the focus control.

  Further, the release button 92, the power switch 94, the mode change switch 96, the cross cursor button 98, and various buttons and switches (generally referred to as “operation unit 90” in the figure) of the forced light emission switch 99 are connected to the CPU 50. Thus, the CPU 50 can always grasp the operation state of the operation unit 90.

  In addition, the digital camera 10 includes a charging unit 160 that is interposed between the strobe 62 and the CPU 50 and charges power for causing the strobe 62 to emit light under the control of the CPU 50. The strobe 62 is also connected to the CPU 50, and the light emission of the strobe 62 is controlled by the CPU 50.

  Next, the overall operation of the digital camera 10 according to the present embodiment will be briefly described.

  First, an image is picked up by the CCD 24 through the optical unit 22, and R (red), G (green), and B (blue) signals indicating the subject image are sequentially output to the analog signal processing unit 26. The analog signal processing unit 26 performs analog signal processing such as correlated double sampling processing on the signal input from the CCD 24 and then sequentially outputs the signal to the ADC 28. The ADC 28 converts the R, G, and B signals input from the analog signal processing unit 26 into 12-bit R, G, and B signals (digital image data) and sequentially outputs the signals to the digital signal processing unit 30. The digital signal processing unit 30 accumulates digital image data sequentially output from the ADC 28 in a built-in line buffer and temporarily stores it in a predetermined area of the memory 72.

  Digital image data stored in a predetermined area of the memory 72 is read out by the digital signal processing unit 30 under the control of the CPU 50, and a white balance is adjusted by applying a digital gain corresponding to a predetermined physical quantity to the gamma data. Processing and sharpness processing are performed to generate 8-bit digital image data, and further YC signal processing is performed to generate a luminance signal Y and chroma signals Cr and Cb (hereinafter referred to as “YC signal”), and a YC signal is generated. The data is stored in an area different from the predetermined area in the memory 72.

  The LCD 44 is configured to display a moving image (through image) obtained by continuous imaging by the CCD 24 and can be used as a finder. However, when the LCD 44 is used as a finder, The generated YC signal is sequentially output to the LCD 44 via the LCD interface 42. As a result, a through image is displayed on the LCD 44.

  Here, when the release button 92 is half-pressed by the user, after the AE function is activated and the exposure state is set as described above, the AF function is activated and focus control is performed, and then the fully-pressed state is continued. In this case, the YC signal stored in the memory 72 at this time is compressed in a predetermined compression format (JPEG format in the present embodiment) by the compression / decompression processing circuit 86 and then passed through the external memory interface 80. Shooting is performed by recording in the memory card 82.

  Next, the camera module 12 will be described.

  As shown in FIG. 3, the camera module 12 includes an optical unit 22, and a CCD 24 is provided behind the optical axis of the lens 21 on the exit side of the optical unit 22. The CCD 24 is soldered to the printed wiring board 13. Further, a BGA package 51 on which a semiconductor chip 57 (IC chip, see FIG. 4) including the analog signal processing unit 26, ADC 28, etc. (see FIG. 2) is mounted is provided with a substrate 300 on which a printed circuit board 52 is mounted. . The printed wiring board 13 and the printed board 52 of the board 300 are electrically connected by the flexible printed wiring board 16. The connector 18 connected to the connector 17 connected to the system bus BUS (see FIG. 2) is soldered to the printed wiring board 19, and the printed circuit board 52 and the printed wiring board 19 are connected by the flexible printed wiring board 40. It is connected. Note that the direction in which the printed wiring board 19 is connected to the connector 17 (the direction of arrow A in the figure) is substantially perpendicular to the printed wiring board 13, the printed board 52, and the like, and the flexible printed wiring board 40 has a bent portion. It is bent at a substantially right angle at 40Z.

  Next, details of the BGA package 51 described above and mounting of the BGA package 51 on the printed circuit board 52 will be described.

  4 is a schematic cross-sectional view showing a state before mounting, and FIG. 5 is a schematic cross-sectional view showing a state after mounting.

  In the BGA package 51, a plurality of bump lands 54 are formed on the upper and lower surfaces of the substrate 53, and the bump lands 54 are connected to each other by a signal via hole 55 and a thermal via 56 that vertically penetrate the substrate 53. It is in a state. Then, a semiconductor chip (IC chip) 57 is mounted on the upper surface side, the semiconductor chip 57 and the bump land 54 are electrically connected by a bonding wire 58, and a substantially entire upper surface side is further formed by a mold resin 59. It is in a sealed state.

  On the other hand, a plurality of lands 61 are formed on the upper and lower surfaces of the printed circuit board 52 by printing. The land 61 on the upper surface corresponds to the bump land 54 formed on the substrate 53 of the BGA package 51.

  6B, the bonding upper surface 102A of the upper flat portion 102 of the leaf spring 100 is soldered to the bump land 54 formed on the substrate 53 of the BGA package 51, and the leaf spring 100 is also joined. The lower bonding portion 104A of the lower flat portion 104 is soldered to a land 61 formed on the upper surface of the printed circuit board 52, so that the BGA package is mounted on the printed circuit board 52 as shown in FIGS. 51 is implemented.

  Next, a mounting method for mounting the BGA package 51 on the printed circuit board 52 will be described. In addition, the left figure of each figure of the following FIG. 7 (A) to (E) is a perspective view, and the right figure is a side view.

[First step]
As shown in FIG. 7A, solder balls 60 are formed in a grid pattern on both surfaces of a conductive plate 200 having a spring property. The plate 200 is plated with gold after being plated with nickel. The solder balls 60 are arranged corresponding to the bump lands 54 formed on the substrate 53 of the BGA package 51.

[Second step]
As shown in FIG. 7B, the bump land 54 formed on the substrate 53 of the BGA package 51 is cut out by pressing, laser processing, etching, or the like on the plate 200 having the solder balls 60 formed on both sides. The leaf springs 200 are formed in an array corresponding to (see FIG. 8).

  As shown in FIG. 9A, the leaf spring 200 has a shape in which a cross portion 108 having a predetermined width is formed inside a circular portion having a predetermined width. The circular portion becomes the upper flat portion 102, and the upper surface of the upper flat portion 102 becomes the bonding upper surface 102 A provided with the solder balls 60 as shown in FIG. 6B. Further, as shown in FIG. 9A, the square portion at the center of the cross portion 108 (intersection portion of the cross) becomes the lower flat portion 104, and the lower surface of the lower flat portion 104 as shown in FIG. 6B. Becomes the lower joint surface 104 A provided with the solder balls 60.

  The upper flat portion 102 and the lower flat portion 104 are bent at the boundary between the intermediate portion 106 (the portion other than the lower flat portion 104 (square portion) of the cross portion 108), and the upper flat portion 102 and the lower flat portion 104 are Is substantially parallel with a predetermined interval. The intermediate portion 106 is not subjected to the above-described gold plating, and the nickel plating applied as a base is exposed.

[Third step]
As shown in FIG. 7C, the bump land 54 of the BGA package 51 is soldered to the bonding upper surface 102A of the leaf spring 100 formed on the plate 200 with solder balls 60, and the leaf spring 100 is soldered to the bump land 54 with solder. Fix it. (See also FIG. 6).

[Fourth step]
As shown in FIG. 7D, the leaf spring 100 joined to the BGA package 51 is extracted from the plate 200.

[Fifth step]
As shown in FIG. 7E, the joint lower surface 104A of the leaf spring 100 soldered to the bump land 54 of the BGA package 51 and the land 61 on the upper surface of the printed circuit board 52 are soldered with solder balls 60, and printed. The mounting of the BGA package 51 on the substrate 52 is completed. (See also FIG. 6).

  Next, the operation of this embodiment will be described.

  As described above, the bonding upper surface 102A of the upper flat portion 102 of the leaf spring 100 is soldered to the bump land 54 formed on the substrate 53 of the BGA package 51, and the lower flat portion 104 of the leaf spring 100 is bonded. The BGA package 51 is mounted on the printed circuit board 52 by soldering the lower surface 104 </ b> A to the land 61 formed on the upper surface of the printed circuit board 52. (See FIGS. 5 and 6).

  Therefore, since the leaf spring 100 is elastically deformed and absorbs the variation in height, the reliability of soldering is high. Furthermore, the stress applied by the difference in thermal expansion between the BGA package 51 and the printed circuit board 52 after mounting is also absorbed by the elastic deformation of the leaf spring 100. Therefore, for example, the solder does not crack or break.

  Furthermore, since the solder balls 60 are formed on the bonding upper surface 102A and the bonding lower surface 104A, the solder hardly moves to the intermediate portion 106. Furthermore, since the intermediate portion 106 is not subjected to gold plating and the underlying nickel plating is exposed, it is difficult for the intermediate portion 106 to be soldered. Therefore, since the solder is hardly attached to the intermediate portion 106, the elastic deformation of the leaf spring 100 is not hindered.

  Further, the leaf spring 100 is soldered to the joining upper surface 102A of the substantially horizontal upper flat portion 102 and the joining lower surface 104A of the lower flat portion 104. In other words, since the soldering surface (joint surface) is flat, it is difficult to tilt during soldering, so that the soldering operation can be performed stably. Also, the soldering strength is high.

  Thus, the reliability of soldering has been remarkably improved over a long period.

  Further, since the plate springs 100 are formed on the plate 200 in an arrangement corresponding to the bump lands 54 formed on the substrate 53 of the BGA package 51, one connection between the bump lands 54 of the BGA package 51 and the small plate springs 100 is performed. There is no need to perform the steps one by one or fix the leaf springs 100 side by side on a jig or the like. That is, the bonding between the bump land 54 of the BGA package 51 and the leaf spring 100 is very easy.

  In addition, this invention is not limited to the said embodiment.

For example, the shape of the leaf spring 100 is not limited to the above embodiment. The variations are shown below.
[First variation]
As shown in FIG. 9 (B), the first variation of the leaf spring 110 has a shape in which an L-shaped portion 118 having a predetermined width is formed inside a circular portion having a predetermined width. This circular portion becomes the upper flat portion 112, and the upper surface of the upper flat portion 112 becomes the bonding upper surface 112A provided with solder balls. Further, the central square portion (the L-curved portion) of the L-shaped portion 118 becomes the lower flat portion 114, and the lower surface of the lower flat portion 114 becomes the bonding lower surface 114A provided with solder balls.

The upper flat portion 112 and the lower flat portion 114 are bent at the boundary portion between the intermediate portion 116 (the portion other than the lower flat portion 114 of the L-shaped portion 118), and the upper flat portion 112 and the lower flat portion 114 are predetermined. It becomes the structure which became substantially parallel with the space | interval. The intermediate portion 116 is not subjected to the above-described gold plating, and the nickel plating applied as a base is exposed.
[Second variation]
As shown in FIG. 9C, the second variation of the leaf spring 120 has a shape in which an I-shaped portion 128 having a predetermined width is formed inside a circular portion having a predetermined width. This circular portion becomes the upper flat portion 122, and the upper surface of the upper flat portion 122 becomes the bonding upper surface 122A provided with solder balls. Further, the square portion at the tip of the I-shaped portion 128 becomes the lower flat portion 124, and the lower surface of the lower flat portion 124 becomes the bonding lower surface 124A provided with solder balls.

The upper flat portion 122 and the lower flat portion 124 are bent at the boundary between the intermediate portion 126 (the portion other than the lower flat portion 124 at the tip of the I-shaped portion 128), and the upper flat portion 122 and the lower flat portion 124 are The configuration is substantially parallel with a predetermined interval. The intermediate portion 126 is not subjected to the above-described gold plating, and the nickel plating applied as a base is exposed.
[Third Variation]
As shown in FIG. 9D, the third variation of the leaf spring 130 includes a spiral portion 138 having a predetermined width. The root of the spiral portion 132 becomes the upper flat portion 132, and the upper surface of the upper flat portion 132 becomes the joining upper surface 132A provided with solder balls. Further, the square portion at the tip of the spiral portion 138 becomes a lower flat portion 134, and the lower surface of the lower flat portion 134 becomes a bonding lower surface 134A provided with solder balls.

  The upper flat portion 132 and the lower flat portion 134 are bent at the boundary portion between the intermediate portion 136 (the portion other than the upper flat portion 132 and the lower flat portion 134 of the spiral portion 132), and the upper flat portion 132 and the lower flat portion 134 are bent. Are substantially parallel with a predetermined interval. The intermediate portion 136 is not subjected to the above-described gold plating, and the nickel plating applied as a base is exposed.

  In the above embodiment, the bump lands 54 of all the BGA packages 51 and the lands 61 on the upper surface of the printed circuit board 52 are joined via the leaf springs 100, 110, 120, 130. However, the present invention is not limited to this. At least a pair of the bump lands 54 of the BGA package 51 and the lands 61 on the upper surface of the printed circuit board 52 are joined via the leaf springs 100, 110, 120, 130, and the other may be ordinary soldering. . For example, between the bump land 54 and the land 61 where the stress due to the thermal expansion difference between the BGA package 51 and the printed circuit board 52 is the most, for example, the bump land 54 and the land 61 at the outermost four corners arranged in a substantially square shape. If it is joined via at least the leaf springs 100, 110, 120, 130, the effect is sufficiently obtained. Moreover, shapes other than the said leaf | plate spring 100,110,120,130 may be sufficient.

  For example, although not shown, only the I-shaped portion 128 having a predetermined width as in the second variation may be formed and the cross section may be a Z-shape. Moreover, the shape provided only with any one of an upper flat part and a lower flat part may be sufficient.

  In addition, the solder ball 60 is formed in advance on the plate 200, but is not limited thereto. For example, when soldering an end portion where the solder ball 60 is not formed and the leaf spring, which is formed only on one of the surfaces, the solder ball is previously applied to the bump land 54 of the BGA package 51 or the printed circuit board 52. You may form in the land 61 of an upper surface. Alternatively, solder balls may be formed in advance on both the bump lands 54 of the BGA package board 51 and the lands 61 on the upper surface of the printed circuit board 52 without being formed in advance on the plate 200.

  Further, although the present invention has been described with respect to the example applied to the substrate 300 of the camera module 12 of the digital camera 10, it can also be applied to other substrates. Furthermore, the present invention can be applied to all electronic devices other than the digital camera 10.

It is an external view of a digital camera provided with the camera module which concerns on embodiment of this invention. It is a schematic block diagram of the control system of a digital camera provided with the camera module which concerns on embodiment of this invention. It is a perspective view which shows the camera module of embodiment of this invention. It is a schematic sectional drawing which shows the state before mounting to the printed circuit board of a BGA package. It is a schematic sectional drawing which shows the state after mounting to the printed circuit board of a BGA package. (A) is a side view which shows the state after mounting to the printed circuit board of a BGA package typically, (B) is an enlarged view of the B section of (A). The method of mounting the BGA package on the printed circuit board is shown in order from (A) to (E). The left figure in each figure of (A) to (E) is a perspective view, and the right figure is a side view. is there. It is the figure which formed the leaf | plate spring in the plate. (A) shows the leaf spring used in the camera module of the embodiment of the present invention, (B) shows the first variation of the leaf spring, (C) shows the second variation of the leaf spring, (D ) Shows a third variation of the leaf spring, the upper view in each of FIGS. (A) to (D) is a top view, and the lower view is a cross-sectional view.

Explanation of symbols

10 Digital Camera 12 Camera Module 51 BGA Package (Package Substrate)
52 Printed circuit board 54 Bump land (Electrode of package board)
57 Semiconductor chip 60 Solder ball 61 Land (Electrode of printed circuit board)
100 Leaf spring 102A Joint upper surface (substantially horizontal plane)
104A Joint upper surface (substantially horizontal plane)
106 Intermediate part 300 Substrate 600 Plate

Claims (10)

A substrate in which a package substrate on which a semiconductor chip is mounted is mounted on a printed circuit board,
The electrode of the package substrate and the electrode of the printed circuit board are joined via a conductive elastic member having a substantially horizontal surface at either one end or the other end, or both ends,
One end of the elastic member is soldered to the electrode of the package substrate, and the other end of the elastic member is soldered to the electrode of the printed circuit board.   The substrate according to claim 1, wherein at least the electrode of the package substrate and the electrode of the printed circuit board to which the stress is applied are joined via the elastic member. The electrode of the outermost package substrate and the electrode of the printed circuit board are arranged in a substantially rectangular shape,
The substrate according to claim 2, wherein at least the electrodes of the package substrate at the four corners of the outermost periphery and the electrodes of the printed circuit board are joined by the elastic member.   4. The substrate according to claim 1, wherein the elastic member includes an intermediate portion between the both ends, to which solder is less likely to adhere than both ends. 5.   The substrate according to any one of claims 1 to 4, wherein the elastic member is a leaf spring.   A camera module comprising the substrate according to any one of claims 1 to 5. A mounting method of a substrate for mounting a package substrate on which a semiconductor chip is mounted on a printed circuit board,
A first step of cutting out a predetermined region of the conductive plate to form a leaf spring in an array corresponding to the electrode of the package substrate;
A second step of soldering one end of the plate spring formed on the plate with a solder ball previously formed on the electrode of the package substrate, and joining the plate spring to the electrode of the package substrate;
A third step of removing the leaf spring joined to the electrode of the package substrate from the plate;
The other end of the leaf spring joined to the first electrode of the package substrate is soldered with a solder ball previously formed on the electrode of the printed circuit board, and the leaf spring is joined to the electrode of the printed circuit board. With four steps,
A method for mounting a substrate, comprising: A mounting method of a substrate for mounting a package substrate on which a semiconductor chip is mounted on a printed circuit board,
A first step of forming solder balls on both sides of the conductive plate;
A second step of cutting out a predetermined region of the plate and forming plate springs having the solder balls at both ends in an arrangement corresponding to the electrodes of the package substrate;
A third step of soldering one end of the leaf spring formed on the plate to the electrode of the package substrate with the solder ball, and joining the leaf spring to the electrode of the package substrate;
A fourth step of removing the leaf spring joined to the electrode of the package substrate from the plate;
A fifth step of soldering the other end of the leaf spring joined to the electrode of the package substrate to the electrode of the printed circuit board with the solder ball, and joining the leaf spring to the electrode of the printed circuit board;
A method for mounting a substrate, comprising: A substrate mounting method for mounting a package substrate on which a semiconductor chip is mounted on a printed circuit board,
A first step of forming solder balls on one side of the conductive plate;
A second step of cutting out a predetermined region of the plate and forming a plate spring having the solder ball at one end in an array corresponding to the electrode of the package substrate;
A third step of soldering one end of the plate spring formed on the plate to the electrode of the package substrate with the solder ball, and joining the plate spring to the electrode of the package substrate;
A fourth step of removing the leaf spring joined to the electrode of the package substrate from the plate;
A fifth step of soldering the other end of the leaf spring joined to the electrode of the package substrate with a solder ball previously formed on the electrode of the printed circuit board, and joining the leaf spring to the electrode of the printed circuit board; ,
A method for mounting a substrate, comprising: A mounting method of a substrate for mounting a package substrate on which a semiconductor chip is mounted on a printed circuit board,
A first step of forming solder balls on the other side of the conductive plate;
A second step of cutting out a predetermined region of the plate and forming a plate spring having the solder ball at the other end in an arrangement corresponding to the electrode of the package substrate;
A third step of soldering one end of the leaf spring formed on the plate with a solder ball previously formed on the electrode of the package substrate, and joining the leaf spring to the electrode of the package substrate;
A fourth step of removing the leaf spring joined to the electrode of the package substrate from the plate;
A fifth step of soldering the other end of the leaf spring joined to the electrode of the package substrate to the electrode of the printed board with the solder ball, and joining the leaf spring to the electrode of the printed board;
A method for mounting a substrate, comprising:

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